Engine Overheating - Chevrolet 4500 HD 2023 Manual

254 Vehicle Care
3. Run the engine until the engine coolant
temperature rises to normal level, and
idle the engine for 10 minutes.
4. Install the radiator cap.
Check, replenish or change the engine
coolant only after the engine has sufficiently
cooled down.
When the engine is still hot, take care to
prevent engine coolant from contact with
the exhaust manifold. Any such contact
could result in exhaust manifold damage.
If you use the proper quality engine coolant,
there is no need to add extra inhibitors or
additives which claim to improve the
system. They may be harmful to the proper
operation of the system.
Do not overfill the engine coolant
reserve tank.
If the level of engine coolant changes
rapidly, have your vehicle inspected at your
dealer.
Thermostat
The engine coolant temperature is controlled
by thermostat(s). The thermostats stop
engine coolant flow through the radiator
until a preset temperature is reached. The
thermostats are installed in the engine
coolant outlet on the engine block. The
same thermostats are used in both winter
and summer. When a replacement is
needed, genuine GM parts are
recommended.
Radiator Pressure Cap
The radiator cap, a 108 kPa (16 psi) pressure
type, must be installed tightly, otherwise
engine coolant may be lost and damage to
the engine may result from overheating. The
radiator pressure cap should be checked
periodically for proper operation. If a
replacement is required, a genuine GM part
is recommended.

Engine Overheating

When the Engine Overheats
The engine cooling system may overheat if
the engine coolant level is too low, if there
is a sudden loss of engine coolant (such as
radiator hose failure), or if other problems
occur. It may also temporarily overheat
during severe operating conditions such as:
Climbing a long hill on a hot day.
Stopping after high-speed driving.
Idling for long periods in traffic.
If engine power drops and the needle on the
engine coolant temperature gauge goes up
above the upper limit of the safety zone
and enters the "H" zone, the engine is
overheating. The engine overheat warning
light will come on and the warning buzzer
will sound. Either steam or boiling engine
coolant will squirt out of the radiator. The
vehicle will also have an OVER HEAT
message displayed. Take the following
corrective actions immediately.
Warning
To help avoid being burned:
Do not tilt the cab or open the engine
access cover if you see or hear steam or
engine coolant escaping from the engine
compartment. Wait until no steam or
engine coolant can be seen or heard
before tilting the cab or opening the
engine cover.
Do not remove the radiator cap or engine
coolant reserve tank cap if the engine
coolant in the tank is boiling. Also do not
remove the radiator cap while the engine
and radiator are still hot. Scalding fluid
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